User manual JBL GTH400

[. . . ] GTH400-20107 06/03/98 15:49 Side 26 GTH400-20107 06/03/98 15:49 Side 1 GTH400 6/5/4/3 CHANNEL AUTOMOTIVE POWER AMPLIFIER OWNER'S MANUAL GTH400 GTH400-20107 06/03/98 15:49 Side 2 Table of Contents 1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. 1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. 2 About Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [. . . ] One crossover is connected in series with the amplifier circuitry and the other crossover is connected to the preamp level output jacks. These crossovers can be set in either the F (full bandwidth operation), L (subwoofer operation), or H (satellite operation). The crossover frequencies are set by chips inside the amplifier. These chips are simply a set of resistors, connected across the pins and molded into a single package. The crossover frequencies may be changed to any value desired by changing the resistor network. Frequency Resistor Value 50Hz 47k 80Hz 33k 120Hz 22k 200Hz 12k 250Hz 10k 375Hz 6. 8k 500Hz 4. 7k 650Hz 3. 9k 2. 5kHz 1k 5kHz 470 JBL Part Number 1-23-750 1-23-817 1-23-820 1-23-821 1-23-810 1-23-822 1-23-815 1-23-823 1-23-824 1-23-816 150H 100K R KE MS EA T CE SP INPUDAN OR 150H PE CT IM SELE MS 100K MS 100K 150H MS shown on the diagram above. This input is also capable of directly accepting signals, when in the 100k ohm setting, from many Balanced Line Drivers such as those sometimes used in competition vehicles. For best results, a Balanced Line Driver capable of at least 4V nominal output should be used. If the head unit has 4 channels of builtin amplification and/or an electronic fader control, you should leave the jumpers in the factory set position. If the head unit has 2 channels of amplification, with a speaker-level fader, the jumpers should be set to the 15-ohm position. This will always be a 12 OU T 100K PR EA MP 150H LINE INPU T GTH400-20107 06/03/98 15:49 Side 13 Custom Chip Construction Regardless of whether you build or buy it, the necessary resistor network has the following configuration: 1. Remove the screws from the bottom panel as shown below. ·Each resistor in the package has the same value. ·If you know the crossover frequency you want, you can calculate the resistor value necessary by solving the following equation: Resistor Value in ohms = 2, 500, 000 Frequency in Hz 2. Select which resistor module, high pass or low pass, that you wish to change. A chip puller, which can be obtained from any electronics store, is recommended to remove the resistor chip. Pull the resistor chip from the socket as shown in the figure below. CR OS SO VE R ·Use the following equation if you have a resistor pack of a known value, and want to find its crossover frequency: Frequency = in Hz 2, 500, 000 Resistor Value in ohms ·To build chips from discrete resistors, solder the resistors to a standard 14pin "DIP Header" according to the diagram. If a DIP Header is not available, you may bend the leads of 1 /4 -watt resistors 90 degrees, trim them to 1/8"-length, and insert them directly into the chip sockets. To change the crossover frequency change the resistor network as follows: 4. Place the new module in the socket making sure all pins are lined up with the socket holes. Press the module firmly into the socket. For further information on how to use the speaker output and preamp output crossovers for system building see the "Typical Applications" and "Add-On and Upgrade Steps" sections. Remote Chassis Installation The wired remote of the GTH400 can be installed either in dash or under dash. HIG H FR FILT PAS SE EQU ER S C LE E MO CT NCY 13 DU ION LE C10 FR FILT PAS SE EQU ER S LE E MO CT NCY DU ION LE LO W NO JB RT L JB HR INC. [. . . ] Check that the power wires are not reversed. 20 GTH400-20107 06/03/98 15:50 Side 21 7. In Case of Difficulty Power-on light does not come on · Head unit not on; turn the head unit on. · Ground wire is disconnected or defective; check for continuity with an ohmmeter between the amplifier's ground terminal and a known chassis ground point. · Battery wire is disconnected or defective; check for approximately +12 volts between the amplifier's battery and ground terminals. [. . . ]